samedi 7 janvier 2017

Image above: NGC 1448, a galaxy with an active galactic nucleus hidden by gas and dust, is seen in this image. Image Credits: Carnegie-Irvine Galaxy Survey/NASA/JPL-Caltech.

Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) mission can detect. That's how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.

"These black holes are relatively close to the Milky Way, but they have remained hidden from us until now," said Ady Annuar, a graduate student at Durham University in the United Kingdom, who presented the results at the American Astronomical Society meeting in Grapevine, Texas. "They're like monsters hiding under your bed."

Both of these black holes are the central engines of what astronomers call "active galactic nuclei," a class of extremely bright objects that includes quasars and blazars. Depending on how these galactic nuclei are oriented and what sort of material surrounds them, they appear very different when examined with telescopes.

Active galactic nuclei are so bright because particles in the regions around the black hole get very hot and emit radiation across the full electromagnetic spectrum -- from low-energy radio waves to high-energy X-rays. However, most active nuclei are believed to be surrounded by a doughnut-shaped region of thick gas and dust that obscures the central regions from certain lines of sight. Both of the active galactic nuclei that NuSTAR recently studied appear to be oriented such that astronomers view them edge-on. That means that instead of seeing the bright central regions, our telescopes primarily see the reflected X-rays from the doughnut-shaped obscuring material.

Image above: This galaxy, called IC 3639, also contains an example of an obscured supermassive black hole. Image Credits: ESO/NASA/JPL-Caltech/STScI.

"Just as we can't see the sun on a cloudy day, we can't directly see how bright these active galactic nuclei really are because of all of the gas and dust surrounding the central engine," said Peter Boorman, a graduate student at the University of Southampton in the United Kingdom.

Boorman led the study of an active galaxy called IC 3639, which is 170 million light years away. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA's Chandra X-Ray Observatory and the Japan-led Suzaku satellite. The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus. NuSTAR also provided the first precise measurement of how much material is obscuring the central engine of IC 3639, allowing researchers to determine how luminous this hidden monster really is.

More surprising is the spiral galaxy that Annuar focused on: NGC 1448. The black hole in its center was only discovered in 2009, even though it is at the center of one of the nearest large galaxies to our Milky Way. By "near," astronomers mean NGC 1448 is only 38 million light years away (one light year is about 6 trillion miles).

Annuar's study discovered that this galaxy also has a thick column of gas hiding the central black hole, which could be part of a doughnut-shaped region. X-ray emission from NGC 1448, as seen by NuSTAR and Chandra, suggests for the first time that, as with IC 3639, there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.

Researchers also found that NGC 1448 has a large population of young (just 5 million year old) stars, suggesting that the galaxy produces new stars at the same time that its black hole feeds on gas and dust. Researchers used the European Southern Observatory New Technology Telescope to image NGC 1448 at optical wavelengths, and identified where exactly in the galaxy the black hole should be. A black hole's location can be hard to pinpoint because the centers of galaxies are crowded with stars. Large optical and radio telescopes can help detect light from around black holes so that astronomers can find their location and piece together the story of their growth.

Nuclear Spectroscopic Telescope Array or NuSTAR. Image Credit: NASA

"It is exciting to use the power of NuSTAR to get important, unique information on these beasts, even in our cosmic backyard where they can be studied in detail," said Daniel Stern, NuSTAR project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. JPL is managed by Caltech for NASA.

vendredi 6 janvier 2017

NASA’s Cyclone Global Navigation Satellite System (CYGNSS) constellation of eight spacecraft made its “first light” measurements of the ocean surface on Jan. 4, 2017. Measurements were made by one of the eight spacecraft, and mission scientists plan to activate the science instruments on the other seven in the near future. Direct measurements are made of the GPS power reflected by the ocean surface, from which near-surface wind speed can be derived over tropical oceans and, in particular, inside hurricanes.

Image above: This image shows “first light” data from NASA’s CYGNSS mission in the form of a Delay Doppler Map produced by one of the eight spacecraft (FM03) that make up the constellation at 15:48:31 UTC (11:48:31 a.m. EST) on Jan. 4, 2017. The peak in the center of the image represents scattered GPS signal from the ocean surface, from which near-surface wind speed can be derived. Image Credit: NASA.

​CYGNSS was launched on Dec. 15, 2016, at 8:37 a.m. EST into a low-inclination, low-Earth orbit over the tropics. The CYGNSS constellation will make frequent and accurate measurements of ocean surface winds in and near a hurricane’s inner core, including regions beneath the eyewall and intense inner rainbands that previously could not be measured from space.

Direct science measurements are displayed as a Delay Doppler Map (DDM), which shows the GPS power reflected by the ocean in the vicinity of the targeted measurement location. One such DDM is shown here, measured by constellation spacecraft FM03 on January 4, 2017, at 11:48:31 a.m. EST/15:48:31 UTC in the South Atlantic Ocean, east of Brazil.

“Our first light DDMs are direct confirmation that the CYGNSS science instrument on FM03 is operating as expected,” said Christopher Ruf, CYGNSS principal investigator at the University of Michigan’s Department of Climate and Space Sciences and Engineering in Ann Arbor. “There are still many steps ahead of us leading to reliable improvements in hurricane forecasts, but this was a critical one and it feels great to have it behind us.”

CYGNSS is the first of the missions competitively selected through NASA’ Earth Venture Program to launch into orbit. The Earth Venture Program is managed by the Earth System Science Pathfinder (ESSP) Program Office at NASA’s Langley Research Center, Hampton, Virginia. This program focuses on low-cost, science-driven missions to enhance our understanding of the current state of the complex, dynamic Earth system and to enable continual improvement in the prediction of future changes.

The CYGNSS mission is led by the University of Michigan, with the Southwest Research Institute in San Antonio, Texas, leading the engineering development and operation of the constellation. The University of Michigan Climate and Space Sciences and Engineering department leads the science investigation, and the Earth Science Division of NASA’s Science Mission Directorate oversees the mission.

Interstellar forecast for a nearby star: Raining comets! NASA’s Hubble Space Telescope has discovered comets plunging onto the star HD 172555, which is a youthful 23 million years old and resides 95 light-years from Earth.

The exocomets — comets outside our solar system — were not directly seen around the star, but their presence was inferred by detecting gas that is likely the vaporized remnants of their icy nuclei.

Image above: This illustration shows several comets speeding across a vast protoplanetary disk of gas and dust and heading straight for the youthful, central star. These "kamikaze" comets will eventually plunge into the star and vaporize. The comets are too small to photograph, but their gaseous spectral "fingerprints" on the star's light were detected by NASA's Hubble Space Telescope. The gravitational influence of a suspected Jupiter-sized planet in the foreground may have catapulted the comets into the star. This star, called HD 172555, represents the third extrasolar system where astronomers have detected doomed, wayward comets. The star resides 95 light-years from Earth. Image Credits: NASA, ESA, A. Feild and G. Bacon (STScI).

HD 172555 represents the third extrasolar system where astronomers have detected doomed, wayward comets. All of the systems are young, under 40 million years old.

The presence of these doomed comets provides circumstantial evidence for “gravitational stirring” by an unseen Jupiter-size planet, where comets deflected by its gravity are catapulted into the star. These events also provide new insights into the past and present activity of comets in our solar system. It’s a mechanism where infalling comets could have transported water to Earth and the other inner planets of our solar system.

Astronomers have found similar plunges in our own solar system. Sun-grazing comets routinely fall into our sun. “Seeing these sun-grazing comets in our solar system and in three extrasolar systems means that this activity may be common in young star systems,” said study leader Carol Grady of Eureka Scientific Inc. in Oakland, California, and NASA's Goddard Spaceflight Center in Greenbelt, Maryland. “This activity at its peak represents a star’s active teenage years. Watching these events gives us insight into what probably went on in the early days of our solar system, when comets were pelting the inner solar system bodies, including Earth. In fact, these star-grazing comets may make life possible, because they carry water and other life-forming elements, such as carbon, to terrestrial planets.”

Grady will present her team’s results Jan. 6 at the winter meeting of the American Astronomical Society in Grapevine, Texas.

The star is part of the Beta Pictoris Moving Group, a collection of stars born from the same stellar nursery. It is the second group member found to harbor such comets. Beta Pictoris, the group’s namesake, also is feasting on exocomets travelling too close. A young gas-giant planet has been observed in that star’s vast debris disk.

The stellar group is important to study because it is the closest collection of young stars to Earth. At least 37.5 percent of the more massive stars in the Beta Pictoris Moving Group either have a directly imaged planet, such as 51 Eridani b in the 51 Eridani system, or infalling star-grazing bodies, or, in the case of Beta Pictoris, both types of objects. The grouping is at about the age that it should be building terrestrial planets, Grady said.

A team of French astronomers first discovered exocomets transiting HD 172555 in archival data gathered between 2004 and 2011 by the European Southern Observatory’s HARPS (High Accuracy Radial velocity Planet Searcher) planet-finding spectrograph. A spectrograph divides light into its component colors, allowing astronomers to detect an object’s chemical makeup. The HARPS spectrograph detected the chemical fingerprints of calcium imprinted in the starlight, evidence that comet-like objects were falling into the star.

As a follow-up to that discovery, Grady’s team used Hubble’s Space Telescope Imaging Spectrograph (STIS) and the Cosmic Origins Spectrograph (COS) in 2015 to conduct a spectrographic analysis in ultraviolet light, which allows Hubble to identify the signature of certain elements. Hubble made two observations, separated by six days.

Hubble detected silicon and carbon gas in the starlight. The gas was moving at about 360,000 miles per hour across the face of the star. The most likely explanation for the speedy gas is that Hubble is seeing material from comet-like objects that broke apart after streaking across the face of the star.

The gaseous debris from the disintegrating comets is vastly dispersed in front of the star. “As transiting features go, this vaporized material is easy to see because it contains very large structures,” Grady said. “This is in marked contrast to trying to find a small transiting exoplanet, where you’re looking for tiny dips in the star’s light.”

Hubble and the sunrise over Earth. Video Credit: ESA

Hubble gleaned this information because the HD 172555 debris disk surrounding the star is slightly inclined to Hubble’s line of sight, giving the telescope a clear view of comet activity.

Grady’s team hopes to use STIS again in follow-up observations to look for oxygen and hydrogen, which would confirm the identity of the disintegrating objects as comets.

“Hubble shows that these star-grazers look and move like comets, but until we determine their composition, we cannot confirm they are comets,” Grady said. “We need additional data to establish whether our star-grazers are icy like comets or more rocky like asteroids.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA Goddard manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Expedition 50 Commander Shane Kimbrough and Flight Engineer Peggy Whitson concluded their spacewalk at 1:55 p.m. EST. During the six-hour and 32-minute spacewalk, the two NASA astronauts successfully installed three new adapter plates and hooked up electrical connections for three of the six new lithium-ion batteries on the International Space Station. They also accomplished several get-ahead tasks, including a photo survey of the Alpha Magnetic Spectrometer.

The new lithium-ion batteries and adapter plates replace the nickel-hydrogen batteries currently used on the station to store electrical energy generated by the station’s solar arrays. Robotic work to update the batteries began in January. This was the first of two spacewalks planned to finalize the installation.

Image above: Spacewalkers Peggy Whitson (left) and Shane Kimbrough were suited up and ready to go before this morning’s spacewalk began at 7:23 a.m. EST. Image Credits: NASA/@Thom_Astro

Kimbrough and Flight Engineer Thomas Pesquet of ESA (European Space Agency) will conduct the second spacewalk on Friday, Jan. 13. NASA Television coverage will begin at 5:30 a.m.

Once again, Kimbrough will be designated extravehicular crew member 1 (EV 1), wearing a suit bearing red stripes for the fourth spacewalk of his career. Pesquet, who will be making the first spacewalk of his career, will be extravehicular crew member 2, and will wear a suit with no stripes.

Space Station Crew Members Conduct a Spacewalk for Battery Replacement on the Outpost

Space station crew members have conducted 196 spacewalks in support of assembly and maintenance of the orbiting laboratory. Spacewalkers have now spent a total of 1,224 hours and 6 minutes working outside the station.

Like anthropologists piecing together the human family tree, astronomers have found that a misfit "skeleton" of a star may link two different kinds of stellar remains. The mysterious object, called PSR J1119-6127, has been caught behaving like two distinct objects -- a radio pulsar and a magnetar -- and could be important to understanding their evolution.

A radio pulsar is type of a neutron star -- the extremely dense remnant of an exploded star -- that emits radio waves in predictable pulses due to its fast rotation. Magnetars, by contrast, are rabble rousers: They have violent, high-energy outbursts of X-ray and gamma ray light, and their magnetic fields are the strongest known in the universe.

"This neutron star wears two different hats," said Walid Majid, astrophysicist at NASA's Jet Propulsion Laboratory, Pasadena, California. "Sometimes it's a pulsar. Sometimes it's a magnetar. This object may tell us something about the underlying mechanism of pulsars in general."

Image above: This artist's concept shows a pulsar, which is like a lighthouse, as its light appears in regular pulses as it rotates. Image Credits: NASA/JPL-Caltech.

Since the 1970s, scientists have treated pulsars and magnetars as two distinct populations of objects. But in the last decade, evidence has emerged that these could be stages in the evolution of a single object. Majid's new study, combined with other observations of the object, suggests that J1119 could be in a never-before-seen transition state between radio pulsar and magnetar. The study was published in the Jan. 1 issue of Astrophysical Journal Letters, and was presented this week at the American Astronomical Society meeting in Grapevine, Texas.

“This is the final missing link in the chain that connects pulsars and magnetars,” said Victoria Kaspi, astrophysicist at McGill University in Montreal, Canada. “It seems like there’s a smooth transition between these two kinds of neutron star behaviors.”

When this mysterious object was discovered in 2000, it appeared to be a radio pulsar. It was mostly quiet and predictable until July 2016, when NASA's Fermi and Swift space observatories observed two X-ray bursts and 10 additional bursts of light at lower energies coming from the object, as reported in a study in the Astrophysical Journal Letters led by Ersin Gogus. An additional 2016 study in the same journal, led by Robert Archibald, also looked at the two X-ray bursts, incorporating observations from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) telescope. This study also suggested that the pulsar was behaving rebelliously -- like a magnetar.

When the outbursts happened, Kaspi excitedly emailed astrophysicist Tom Prince at JPL/Caltech in Pasadena, telling him this would be a good object to study from the southern hemisphere. Prince, Majid and colleagues used the NASA Deep Space Network 70-meter radio telescope in Canberra, Australia -- the largest dish in the southern hemisphere -- to see what was going on.

"We think these X-ray bursts happened because the object's enormous magnetic field got twisted as the object was spinning," Majid said.

The stress of a twisting magnetic field is so great that it causes the outer crust of the neutron star to break -- analogous to tectonic plates on Earth causing earthquakes. This causes an abrupt change in rotation, called a "glitch," which has been measured by NuSTAR.

Neutron stars are so dense that one teaspoon weighs as much as a mountain. The star's crust, roughly 0.6 miles (1 kilometer) thick, with higher pressure and density at greater depths, is a neutron-rich lattice. This particular neutron star is thought to have one of the strongest magnetic fields among the population of known pulsars: a few trillion times stronger than the magnetic field of the sun.

Two weeks after the X-ray outburst, Majid and colleagues tracked the object's emissions at radio frequencies, which are much lower in energy than X-rays. The radio emissions had sharp increases and decreases in intensity, allowing scientists to quantify how the emission evolved. Researchers used an instrument, which they informally call a "pulsar machine," that was recently installed at the same DSN dish in Australia.

"Within 10 days, something completely changed in the pulsar," Majid said. “It had started behaving like a normal radio pulsar again."

NASA's Swift spacecraft. Image Credit: NASA

The question remains: Which came first, the pulsar or the magnetar? Some scientists argue that objects like J1119 begin as magnetars and gradually stop outbursting X-rays and gamma rays over time. But others propose the opposite theory: that the radio pulsar comes first and, over time, its magnetic field emerges from the supernova’s rubble, and then the magnetar-like outbursts begin. But, just as babies grow to be adults and not vice versa, there is likely a single path for these objects to take.

To help solve this mystery, much as anthropologists study the remains of human ancestors at different stages of evolutionary history, astronomers want to find more “missing link” objects like J1119. This particular object was likely formed following a supernova 1,600 years ago. Monitoring similar objects may shed light on whether this phenomenon is specific to J1119, or whether this behavior is common in this class of objects.

Astronomers continue to monitor J1119 as well. Majid and colleagues observed in December a marked brightening of emissions at radio wavelengths, in a pattern consistent with other magnetars.

"Our recent observations show that this object contains a bit of the 'astrophysical DNA' of two different families of neutron stars," Prince said. "We are looking forward to finding other examples of this type of transitional object."

Powerful solar storms can charge up the soil in frigid, permanently shadowed regions near the lunar poles, and may possibly produce "sparks" that could vaporize and melt the soil, perhaps as much as meteoroid impacts, according to NASA-funded research. This alteration may become evident when analyzing future samples from these regions that could hold the key to understanding the history of the moon and solar system.

The Moon's Permanently Shadowed Regions

Video above: As you watch the Moon over the course of a month, you'll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun's light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA's Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail. Video Credits: NASA Goddard/LRO mission.

The moon has almost no atmosphere, so its surface is exposed to the harsh space environment. Impacts from small meteoroids constantly churn or "garden" the top layer of the dust and rock, called regolith, on the moon. "About 10 percent of this gardened layer has been melted or vaporized by meteoroid impacts," said Andrew Jordan of the University of New Hampshire, Durham. "We found that in the moon’s permanently shadowed regions, sparks from solar storms could melt or vaporize a similar percentage." Jordan is lead author of a paper on this research published online in Icarus August 31, 2016.

Image above: This is a map showing the permanently shadowed regions (blue) that cover about three percent of the moon's south pole. Image Credits: NASA Goddard/LRO mission.

Explosive solar activity, like flares and coronal mass ejections, blasts highly energetic, electrically charged particles into space. Earth's atmosphere shields us from most of this radiation, but on the moon, these particles -- ions and electrons -- slam directly into the surface. They accumulate in two layers beneath the surface; the bulky ions can't penetrate deeply because they are more likely to hit atoms in the regolith, so they form a layer closer to the surface while the tiny electrons slip through and form a deeper layer. The ions have positive charge while the electrons carry negative charge. Since opposite charges attract, normally these charges flow towards each other and balance out.

In August 2014, however, Jordan's team published simulation results predicting that strong solar storms would cause the regolith in the moon's permanently shadowed regions (PSRs) to accumulate charge in these two layers until explosively released, like a miniature lightning strike. The PSRs are so frigid that regolith becomes an extremely poor conductor of electricity. Therefore, during intense solar storms, the regolith is expected to dissipate the build-up of charge too slowly to avoid the destructive effects of a sudden electric discharge, called dielectric breakdown. The research estimates the extent that this process can alter the regolith.

"This process isn't completely new to space science -- electrostatic discharges can occur in any poorly conducting (dielectric) material exposed to intense space radiation, and is actually the leading cause of spacecraft anomalies," said Timothy Stubbs of NASA's Goddard Space Flight Center in Greenbelt, Maryland, a co-author of the paper. The team's analysis was based on this experience. From spacecraft studies and analysis of samples from NASA's Apollo lunar missions, the researchers knew how often large solar storms occur. From previous lunar research, they estimated that the top millimeter of regolith would be buried by meteoroid impacts after about a million years, so it would be too deep to be subject to electric charging during solar storms. Then they estimated the energy that would be deposited over a million years by both meteoroid impacts and dielectric breakdown driven by solar storms, and found that each process releases enough energy to alter the regolith by a similar amount.

"Lab experiments show that dielectric breakdown is an explosive process on a tiny scale," said Jordan. "During breakdown, channels could be melted and vaporized through the grains of soil. Some of the grains may even be blown apart by the tiny explosion. The PSRs are important locations on the moon, because they contain clues to the moon's history, such as the role that easily vaporized material like water has played. But to decipher that history, we need to know in what ways PSRs are not pristine; that is, how they have been weathered by the space environment, including solar storms and meteoroid impacts."

NASA's Lunar Reconnaissance Orbiter (LRO). Image Credit: NASA

The next step is to search for evidence of dielectric breakdown in PSRs and determine if it could happen in other areas on the moon. Observations from NASA's Lunar Reconnaissance Orbiter spacecraft indicate that the soil in PSRs is more porous or "fluffy" than other areas, which might be expected if breakdown was blasting apart some of the soil grains there. However, experiments, some already underway, are needed to confirm that breakdown is responsible for this. Also, the lunar night is long -- about two weeks -- so it can become cold enough for breakdown to occur in other areas on the moon, according to the team. There may even be "sparked" material in the Apollo samples, but the difficulty would be determining if this material was altered by breakdown or a meteoroid impact. The team is working with scientists at the Johns Hopkins University Applied Physics Laboratory on experiments to see how breakdown affects the regolith and to look for any tell-tale signatures that could distinguish it from the effects of meteoroid impacts.

NASA funded the research through the Lunar Reconnaissance Orbiter (LRO) mission and the Solar System Exploration Research Virtual Institute (SSERVI) Dynamic Response of the Environments at Asteroids, the Moon, and Mars 2 (DREAM2) center at NASA Goddard. SSERVI is headquartered out of NASA’s Ames Research Center, Moffett Field, California. LRO is managed by NASA Goddard as a project under NASA's Discovery Program. The Discovery Program is managed by NASA's Marshall Spaceflight Center in Huntsville, Alabama, for the Science Mission Directorate at NASA Headquarters in Washington.

Image above: Here is a view of Earth and its moon, as seen from Mars. It combines two images acquired on Nov. 20, 2016, by the HiRISE camera on NASA's Mars Reconnaissance Orbiter, with brightness adjusted separately for Earth and the moon to show details on both bodies. Relative sizes and distance are correct. Image Credits: NASA/JPL-Caltech/Univ. of Arizona.

From the most powerful telescope orbiting Mars comes a new view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon.

The image combines two separate exposures taken on Nov. 20, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The images were taken to calibrate HiRISE data, since the reflectance of the moon's Earth-facing side is well known. For presentation, the exposures were processed separately to optimize detail visible on both Earth and the moon. The moon is much darker than Earth and would barely be visible if shown at the same brightness scale as Earth.

The combined view retains the correct positions and sizes of the two bodies relative to each other. The distance between Earth and the moon is about 30 times the diameter of Earth. Earth and the moon appear closer than they actually are in this image because the observation was planned for a time at which the moon was almost directly behind Earth, from Mars' point of view, to see the Earth-facing side of the moon.

In the image, the reddish feature near the middle of the face of Earth is Australia. When the component images were taken, Mars was about 127 million miles (205 million kilometers) from Earth.

Mars Reconnaissance Orbiter (MRO). Image Credits: NASA/JPL-Caltech

With HiRISE and five other instruments, the Mars Reconnaissance Orbiter has been investigating Mars since 2006.

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp. of Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it. For additional information about the project, visit: http://mars.nasa.gov/mro

NASA’s two Voyager spacecraft are hurtling through unexplored territory on their road trip beyond our solar system. Along the way, they are measuring the interstellar medium, the mysterious environment between stars. NASA’s Hubble Space Telescope is providing the road map – by measuring the material along the probes’ future trajectories. Even after the Voyagers run out of electrical power and are unable to send back new data, which may happen in about a decade, astronomers can use Hubble observations to characterize the environment of through which these silent ambassadors will glide.

A preliminary analysis of the Hubble observations reveals a rich, complex interstellar ecology, containing multiple clouds of hydrogen laced with other elements. Hubble data, combined with the Voyagers, have also provided new insights into how our sun travels through interstellar space.

Image above: In this artist's conception, NASA's Voyager 1 spacecraft has a bird's-eye view of the solar system. The circles represent the orbits of the major outer planets: Jupiter, Saturn, Uranus, and Neptune. Launched in 1977, Voyager 1 visited the planets Jupiter and Saturn. The spacecraft is now 13 billion miles from Earth, making it the farthest and fastest-moving human-made object ever built. In fact, Voyager 1 is now zooming through interstellar space, the region between the stars that is filled with gas, dust, and material recycled from dying stars. Image Credits: NASA, ESA, and G. Bacon (STScI).

“This is a great opportunity to compare data from in situ measurements of the space environment by the Voyager spacecraft and telescopic measurements by Hubble,” said study leader Seth Redfield of Wesleyan University in Middletown, Connecticut. “The Voyagers are sampling tiny regions as they plow through space at roughly 38,000 miles per hour. But we have no idea if these small areas are typical or rare. The Hubble observations give us a broader view because the telescope is looking along a longer and wider path. So Hubble gives context to what each Voyager is passing through.”

The astronomers hope that the Hubble observations will help them characterize the physical properties of the local interstellar medium. “Ideally, synthesizing these insights with in situ measurements from Voyager would provide an unprecedented overview of the local interstellar environment,” said Hubble team member Julia Zachary of Wesleyan University.

The team’s results will be presented Jan. 6 at the winter meeting of the American Astronomical Society in Grapevine, Texas.

NASA launched the twin Voyager 1 and 2 spacecraft in 1977. Both explored the outer planets Jupiter and Saturn. Voyager 2 went on to visit Uranus and Neptune.

Image above: In this illustration oriented along the ecliptic plane, NASA's Hubble Space Telescope looks along the paths of NASA's Voyager 1 and 2 spacecraft as they journey through the solar system and into interstellar space. Hubble is gazing at two sight lines (the twin cone-shaped features) along each spacecraft's path. The telescope's goal is to help astronomers map interstellar structure along each spacecraft's star-bound route. Each sight line stretches several light-years to nearby stars. Image Credits: NASA, ESA, and Z. Levay (STScI).

The pioneering Voyager spacecraft are currently exploring the outermost edge of the sun’s domain . Voyager 1 is now zooming through interstellar space, the region between the stars that is filled with gas, dust, and material recycled from dying stars.

Voyager 1 is 13 billion miles from Earth, making it the farthest human-made object ever built. In about 40,000 years, after the spacecraft will no longer be operational and will not be able to gather new data, it will pass within 1.6 light-years of the star Gliese 445, in the constellation Camelopardalis. Its twin, Voyager 2, is 10.5 billion miles from Earth, and will pass 1.7 light-years from the star Ross 248 in about 40,000 years.

For the next 10 years, the Voyagers will be making measurements of interstellar material, magnetic fields and cosmic rays along their trajectories. Hubble complements the Voyagers’ observations by gazing at two sight lines along each spacecraft’s path to map interstellar structure along their star-boundroutes. Each sight line stretched several light-years to nearby stars. Sampling the light from those stars, Hubble’s Space Telescope Imaging Spectrograph measures how interstellar material absorbs some of the starlight, leaving telltale spectral fingerprints.

Hubble found that Voyager 2 will move out of the interstellar cloud that surrounds the solar system in a couple thousand years. The astronomers, based on Hubble data, predict that the spacecraft will spend 90,000 years in a second cloud and pass into a third interstellar cloud.

An inventory of the clouds’ composition reveals slight variations in the abundances of the chemical elements contained in the structures. “These variations could mean the clouds formed in different ways, or from different areas, and then came together,” Redfield said.

Hubble orbiting Earth. Video Credit: ESA

An initial look at the Hubble data also suggests that the sun is passing through clumpier material in nearby space, which may affect the heliosphere, the large bubble containing our solar system that is produced by our sun’s powerful solar wind. At its boundary, called the heliopause, the solar wind pushes outward against the interstellar medium. Hubble and Voyager 1 made measurements of the interstellar environment beyond this boundary, where the wind comes from stars other than our sun.

“I’m really intrigued by the interaction between stars and the interstellar environment,” Redfield said. “These kinds of interactions are happening around most stars, and it is a dynamic process.”

The heliosphere is compressed when the sun moves through dense material, but it expands back out when the star passes through low-density matter. This expansion and contraction is caused by the interaction between the outward pressure of the stellar wind, composed of a stream of charged particles, and the pressure of the interstellar material surrounding a star.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C. The Voyagers were built by JPL, which continues to operate both spacecraft. JPL is a division of Caltech.

For images and more information about the local interstellar medium and Hubble, visit:

As 2017 begins, CERN looks forward to a bright year ahead. In 2016, the Laboratory saw record-breaking achievements across the diverse scientific programme, including the excellent performance of the Large Hadron Collider (LHC) producing 7 quadrillion proton–proton collisions.

"Last year was a great one with much progress, and this year is equally full of promise," said Fabiola Gianotti, CERN Director-General.

The Large Hadron Collider (LHC) 27 km of diameter. Image Credit: CERN

In 2017, the LHC will continue to produce a wealth of data at unprecedented energies. The biggest and most powerful accelerator in the world will start again in the spring, following its current maintenance period, known as the extended year end technical stop (EYETS).

Many exciting scientific and technological accomplishments lie ahead, and CERN looks forward to another year of brilliant performance across the varied work of the Laboratory. With LHC experiments exploring new territories of energies, alongside experiments exploring antimatter, astroparticle physics and more, the year looks set to reap new results to enrich the universal encyclopaedia of knowledge.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

jeudi 5 janvier 2017

Two Expedition 50 astronauts are in final preparations for the first of two power maintenance spacewalks that starts Friday at 7 a.m. EST. Astronauts Shane Kimbrough and Peggy Whitson will stow and replace power gear during the first 6.5 hour spacewalk. The duo will work near the solar arrays on the starboard truss segment.

The two spacewalkers will be assisted by ESA astronaut Thomas Pesquet and cosmonaut Oleg Novitskiy from inside the International Space Station. Pesquet will conduct the second spacewalk Jan. 13 with Kimbrough to wrap up the battery installation work. The majority of the complex power upgrade work was done by controllers on the ground remotely using the Canadarm2 robotic arm and hand.

The three cosmonauts worked on an array of station maintenance tasks and advanced space experiments. Cosmonauts Andrey Borisenko and Sergey Ryzhikov researched how blood flow and respiration is affected by living in space. Novitskiy explored the station’s magnetic field and how it affects navigation.

A team of researchers has compiled a special catalog to help astronomers figure out the true distances to tens of thousands of galaxies beyond our own Milky Way.

The catalog, called NED-D, is a critical resource, not only for studying these galaxies, but also for determining the distances to billions of other galaxies strewn throughout the universe. As the catalog continues to grow, astronomers can increasingly rely on it for ever-greater precision in calculating both how big the universe is and how fast it is expanding. NED-D is part of the NASA/IPAC Extragalactic Database (NED), an online repository containing information on more than 100 million galaxies.

Image above: This graphic shows all the cosmic light sources in the sky that are included in the NASA/IPAC Extragalactic Database (NED), an online repository containing information on over 100 million galaxies. Image Credits: NASA/JPL-Caltech.

"We're thrilled to present this catalog of distances to galaxies as a valuable resource to the astronomical community," said Ian Steer, NED team member, curator of NED-D, and lead author of a new report about the database appearing in The Astronomical Journal. "Learning a cosmic object's distance is key to understanding its properties."

Steer and colleagues presented the paper this week at the 229th meeting of the American Astronomical Society in Grapevine, Texas.

Since other galaxies are extremely far away, there's no tape measure long enough to measure their distances from us. Instead, astronomers rely on extremely bright objects, such as Type La supernovae and pulsating stars called Cepheids variables, as indicators of distance. To calculate how far away a distant galaxy is, scientists use known mathematical relationships between distance and other properties of objects, such as their total emitted energy. More objects useful for these calculations have emerged in recent years. NED-D has revealed that there are now more than six dozen different indicators used to estimate such distances.

NED-D began as a small database pulled together in 2005 by Steer. He began serving at NED the following year to build out the database, poring over the scores of astronomical studies posted online daily, identifying newly calculated distance estimates as well as fresh analyses of older data.

From its humble origins a little over a decade ago, NED-D now hosts upwards of 166,000 distance estimates for more than 77,000 galaxies, along with estimates for some ultra-distant supernovae and energetic gamma ray bursts. To date, NED-D has been cited by researchers in hundreds of studies.

Besides providing a one-stop tabulation of the ever-increasing distance estimates published in the astronomical literature, NED-D -- as well as the broader NED -- can serve as "discovery engines." By pooling tremendous amounts of searchable data, the information repositories can allow scientists to identify novel, exotic phenomena that otherwise would get lost in a deluge of observations. An example is the discovery of "super luminous" spiral galaxies by NED team members, reported last year, which were identified among nearly a million individual galaxies in the NED database.

"NED and its associated databases, including NED-D, are in the process of transforming from data look-up services to legitimate discovery engines for science," said Steer. "Using NED today, astronomers can sift through mountains of 'big data' and discover additional new and amazing perspectives on our universe."

MAG observations of Earth's geomagnetic field strength are an important part of NOAA’s space weather mission, with the data used in space weather forecasting, model validation and for developing new space weather models. The GOES-16 MAG samples five times faster than previous GOES magnetometers, which increases the range of space weather phenomena that can be measured. (You can learn more about the GOES-16's magnetometer at http://www.goes-r.gov/products/baseline-geomagnetic-field.html.)

Earth’s geomagnetic field acts as a shield, protecting us from hazardous incoming solar radiation. Geomagnetic storms, caused by eruptions on the surface of the sun, can interfere with communications and navigation systems, cause damage to satellites, cause health risks to astronauts and threaten power utilities. When a solar flare occurs, GOES-16 will tell space weather forecasters where it happened on the sun and how strong it was. Using that information, forecasters can determine if the explosion of energy is coming toward Earth or not.

Image above: Artist's concept of GOES-16. Image Credits: NASA.

GOES-R, a National Oceanic and Atmospheric Administration mission, is the first spacecraft in a new series of NASA-built advanced geostationary weather satellites. NASA successfully launched GOES-R at 6:42 p.m. EST on Nov. 19, 2016, from Cape Canaveral Air Force Station in Florida. NOAA manages the GOES-R Series Program through an integrated NOAA-NASA office. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, oversees the acquisition of the GOES-R series spacecraft and instruments.

For the first time since the twin Voyager spacecraft missions in 1979, scientists have produced far-infrared maps of Jupiter using NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA. These maps were created from the researchers’ studies of the circulation of gases within the gas giant planet’s atmosphere.

Infrared observations provide details not possible at other wavelengths. When gas planets like Jupiter are studied with visible light, they can only see the light reflecting from the top of the gas clouds that make up the atmosphere. Using infrared light allows scientists to see past the clouds and into the deep layers of the atmosphere, providing a three-dimensional view of the planet and the ability to study how gasses circulate within the atmosphere.

Leigh N. Fletcher from the University of Leicester, England, led a team of researchers that used the SOFIA telescope and data from the Faint Object infraRed Camera for the SOFIA Telescope, known as FORCAST, to make these observations. Fletcher’s team was looking for the two types of molecular hydrogen, called “para” and “ortho” – differentiated by whether their protons have aligned or opposite spins. The fraction of hydrogen in the “para” flavor is a good indicator for gasses upwelling from deep within the planet’s atmosphere. This interaction of gas molecules was observed at infrared wavelengths between 17 and 37 microns, a spectrum range that is largely inaccessible to ground-based telescopes.

Much of the current understanding of Jupiter’s circulation patterns are based on results from space-based missions of the past, including the Voyager mission, Galileo mission (1989–2003), and the Cassini spacecraft, which flew past Jupiter in 2000. SOFIA’s airborne location, above more than 99 percent of Earth’s infrared-blocking water vapor, combined with the powerful FORCAST instrument, provides one of the only current facilities capable of studying Jupiter’s overall atmospheric circulation. These new SOFIA observations allow comparisons of how Jupiter’s atmospheric circulation has changed over time.

Images above: Jupiter was observed with SOFIA by stepping the FORCAST spectroscopic slit across the planet. The left-hand panel shows a visible-light image of Jupiter with blue rectangles illustrating the orientation and size of the FORCAST slit. For each pointing of the telescope, the spectrum was made at every position along the slit. The two right-hand panels show SOFIA images of Jupiter made from combining the wavelengths in two of the slits. Jupiter's Great Red Spot is evident and has rotated between the different observations. The total information content is full images of Jupiter at all wavelengths between 17.9 and 32.9 microns, or equivalently, spectra at each position.Images Credits: Visible light image: Anthony Wesley. FORCAST slitscan: NASA/SOFIA/Fletcher et al.

Images from SOFIA reveal several interesting features. The cold, red spot in the southern hemisphere indicates an upwelling of gas that is cooling the atmosphere. The belt zone structure near the equator shows that the equator is cold and surrounded by warm belts of sinking gas. The atmospheric heating from Jovian aurora in the northern reaches of the planet indicates the presence of methane and ethane in the stratosphere. SOFIA’s unique observations of the comparison between ortho and para hydrogen reveal a gradual trend from the equatorial to polar regions.

Based upon earlier observations, Fletcher’s research team assumed that Jupiter should have equilibrium everywhere in its atmosphere, but they found that at low latitudes in the tropics there is significant mixing. Aureoles may be affecting this mixing, but further observations are necessary to better understand the processes over time. The results from the Fletcher team’s observations were recently published in the journal Icarus.

“These results demonstrate that from Earth we can now capture a similar quality of spatially resolved observations as we can obtain from space missions like Voyager,” said Fletcher. “These SOFIA observations will fill the gap in the wavelength coverage of current and future space-based observatories and provide spatial and temporal context for them.”

SOFIA is a Boeing 747SP jetliner modified to carry a 100-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program along with science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is based at NASA Armstrong Flight Research Center's Hangar 703, in Palmdale, California.

Astronomers using NASA’s Chandra X-ray Observatory are uncovering secrets of some of the most mysterious and exciting X-ray spewing objects in the universe. Here are two latest findings presented at the 229th American Astronomical Society meeting in Grapevine, Texas this week.

Astronomers have discovered a cosmic one-two punch unlike any ever seen before. Two of the most powerful phenomena in the Universe, a supermassive black hole, and the collision of giant galaxy clusters, have combined to create a stupendous cosmic particle accelerator.

By combining data from Chandra, the Giant Metrewave Radio Telescope (GMRT) in India, the NSF's Karl G. Jansky Very Large Array, and other telescopes, researchers have found out what happens when matter ejected by a giant black hole is swept up in the merger of two enormous galaxy clusters.

An unparalleled image from Chandra gives astronomers the best look yet at the growth of black holes over billions of years beginning soon after the Big Bang. This is the deepest X-ray image ever obtained, collected with about 7 million seconds, or eleven and a half weeks, of Chandra observing time.

The image comes from what is known as the Chandra Deep Field-South. The central region of the image contains the highest concentration of supermassive black holes ever seen, equivalent to about 5,000 objects that would fit into the area of the full Moon and about a billion over the entire sky.

mercredi 4 janvier 2017

NASA has selected two missions that have the potential to open new windows on one of the earliest eras in the history of our solar system – a time less than 10 million years after the birth of our sun. The missions, known as Lucy and Psyche, were chosen from five finalists and will proceed to mission formulation, with the goal of launching in 2021 and 2023, respectively.

“Lucy will visit a target-rich environment of Jupiter’s mysterious Trojan asteroids, while Psyche will study a unique metal asteroid that’s never been visited before,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “This is what Discovery Program missions are all about – boldly going to places we’ve never been to enable groundbreaking science.”

Image above: (Left) An artist’s conception of the Lucy spacecraft flying by the Trojan Eurybates – one of the six diverse and scientifically important Trojans to be studied. Trojans are fossils of planet formation and so will supply important clues to the earliest history of the solar system. (Right) Psyche, the first mission to the metal world 16 Psyche will map features, structure, composition, and magnetic field, and examine a landscape unlike anything explored before. Psyche will teach us about the hidden cores of the Earth, Mars, Mercury and Venus. Image Credits: SwRI and SSL/Peter Rubin.

Lucy, a robotic spacecraft, is scheduled to launch in October 2021. It’s slated to arrive at its first destination, a main belt asteroid, in 2025. From 2027 to 2033, Lucy will explore six Jupiter Trojan asteroids. These asteroids are trapped by Jupiter’s gravity in two swarms that share the planet’s orbit, one leading and one trailing Jupiter in its 12-year circuit around the sun. The Trojans are thought to be relics of a much earlier era in the history of the solar system, and may have formed far beyond Jupiter’s current orbit.

“This is a unique opportunity,” said Harold F. Levison, principal investigator of the Lucy mission from the Southwest Research Institute in Boulder, Colorado. “Because the Trojans are remnants of the primordial material that formed the outer planets, they hold vital clues to deciphering the history of the solar system. Lucy, like the human fossil for which it is named, will revolutionize the understanding of our origins.”

Lucy will build on the success of NASA’s New Horizons mission to Pluto and the Kuiper Belt, using newer versions of the RALPH and LORRI science instruments that helped enable the mission’s achievements. Several members of the Lucy mission team also are veterans of the New Horizons mission. Lucy also will build on the success of the OSIRIS-REx mission to asteroid Bennu, with the OTES instrument and several members of the OSIRIS-REx team.

NASA's New Discovery Missions

The Psyche mission will explore one of the most intriguing targets in the main asteroid belt – a giant metal asteroid, known as 16 Psyche, about three times farther away from the sun than is the Earth. This asteroid measures about 130 miles (210 kilometers) in diameter and, unlike most other asteroids that are rocky or icy bodies, is thought to be comprised mostly of metallic iron and nickel, similar to Earth’s core. Scientists wonder whether Psyche could be an exposed core of an early planet that could have been as large as Mars, but which lost its rocky outer layers due to a number of violent collisions billions of years ago.

The mission will help scientists understand how planets and other bodies separated into their layers – including cores, mantles and crusts – early in their histories.

“This is an opportunity to explore a new type of world – not one of rock or ice, but of metal,” said Psyche Principal Investigator Lindy Elkins-Tanton of Arizona State University in Tempe. “16 Psyche is the only known object of its kind in the solar system, and this is the only way humans will ever visit a core. We learn about inner space by visiting outer space.”

Psyche, also a robotic mission, is targeted to launch in October of 2023, arriving at the asteroid in 2030, following an Earth gravity assist spacecraft maneuver in 2024 and a Mars flyby in 2025.

In addition to selecting the Lucy and Psyche missions for formulation, the agency will extend funding for the Near Earth Object Camera (NEOCam) project for an additional year. The NEOCam space telescope is designed to survey regions of space closest to Earth’s orbit, where potentially hazardous asteroids may be found.

“These are true missions of discovery that integrate into NASA’s larger strategy of investigating how the solar system formed and evolved,” said NASA’s Planetary Science Director Jim Green. “We’ve explored terrestrial planets, gas giants, and a range of other bodies orbiting the sun. Lucy will observe primitive remnants from farther out in the solar system, while Psyche will directly observe the interior of a planetary body. These additional pieces of the puzzle will help us understand how the sun and its family of planets formed, changed over time, and became places where life could develop and be sustained – and what the future may hold.”

Discovery Program class missions like these are relatively low-cost, their development capped at about $450 million. They are managed for NASA’s Planetary Science Division by the Planetary Missions Program Office at Marshall Space Flight Center in Huntsville, Alabama. The missions are designed and led by a principal investigator, who assembles a team of scientists and engineers, to address key science questions about the solar system.

The Discovery Program portfolio includes 12 prior selections such as the MESSENGER mission to study Mercury, the Dawn mission to explore asteroids Vesta and Ceres, and the InSight Mars lander, scheduled to launch in May 2018.

NASA’s other missions to asteroids began with the NEAR orbiter of asteroid Eros, which arrived in 2000, and continues with Dawn, which orbited Vesta and now is in an extended mission phase at Ceres. The OSIRIS-REx mission, which launched on Sept. 8, 2016, is speeding toward a 2018 rendezvous with the asteroid Bennu, and will deliver a sample back to Earth in 2023. Each mission focuses on a different aspect of asteroid science to give scientists the broader picture of solar system formation and evolution.

Using a model similar to what meteorologists use to forecast weather and a computer simulation of the physics of evaporating ices, scientists have found evidence of snow and ice features on Pluto that, until now, had only been seen on Earth.

Formed by erosion, the features, known as “penitentes,” are bowl-shaped depressions with blade-like spires around the edge that rise several hundreds of feet.

The research, led by John Moores of York University, Toronto, and done in collaboration with scientists at the Johns Hopkins University Applied Physics Laboratory and NASA Goddard Space Flight Center, indicates that these icy features may also exist on other planets where environmental conditions are similar.

The identification of these ridges in Pluto’s informally named Tartarus Dorsa area suggests that the presence of an atmosphere is necessary for the formation of penitentes – which Moores says would explain why they have not previously been seen on other airless icy satellites or dwarf planets. “But exotic differences in the environment give rise to features with very different scales,” he adds. “This test of our terrestrial models for penitentes suggests that we may find these features elsewhere in the solar system, and in other solar systems, where the conditions are right."

The research team, which also includes York’s Christina Smith, Anthony Toigo of APL and Scott Guzewich of Goddard Space Flight Center, compared its model to ridges on Pluto imaged by NASA’s New Horizons spacecraft in 2015. Pluto’s ridges are much larger – more than 1,600 feet (about 500 meters) tall and separated by two to three miles (about three to five kilometers) – than their Earthly counterparts.

“This gargantuan size is predicted by the same theory that explains the formation of these features on Earth,” says Moores. “In fact, we were able to match the size and separation, the direction of the ridges, as well as their age: three pieces of evidence that support our identification of these ridges as penitentes.”

Moores says though Pluto's environment is very different from Earth’s -- it is much colder, the air much thinner, the sun much dimmer and the snow and ice on the surface are made from methane and nitrogen instead of water -- the same laws of nature apply. He adds that both NASA and APL were instrumental in the collaboration that led to this new finding; both provided background information on Pluto's atmosphere using a model similar to what meteorologists use to forecast weather on Earth. This was one of the key ingredients in Moores’ own models of the penitentes, without which this discovery would not have been made.